1. Model Definition

• D634: ISO 4401‑05 direct drive servo valve series

• 392: High flow rating (top model in D634 series)

• C: Revision C

2. Hydraulic Specifications

• Mounting: ISO 4401‑05 (NG10)

• Max working pressure (P, A, B): 350 bar (5,000 psi)

• T‑port pressure (without Y port): ≤ 50 barMoog Inc.

• T‑port pressure (with Y port): ≤ 350 barMoog Inc.

• Rated flow (Δp = 35 bar per land): 360 L/min

• Peak flow (max): ≈ 480 L/min

• Internal leakage (at null): ≤ 6.5 L/min

• Fluid: ISO 11158 mineral oil (DIN 51524)

• Fluid temperature: −20 °C … +80 °C

• Fluid cleanliness: ISO 4406 17/14/11 (recommended 15/12 or better)

• Weight: ≈ 9.2 kg

3. Dynamic Performance (typical)

• Full‑stroke step response (0 → 100%): ≤ 14 msMoog Inc.

• −3 dB bandwidth: 75–85 Hz

• Hysteresis: < 0.20% full scale

• Resolution: < 0.10% full scale

• Null drift (ΔT = 55 K): < 1.2% full scale

4. Electrical Specifications

• Supply voltage: 24 VDC (18–32 VDC)Moog Inc.

• Max operating current: 5.0 A

• External fuse: 6.3 A slow‑blow

• Command signal (standard): ±10 VDCMoog Inc.

• Optional command: ±10 mA / 4–20 mAMoog Inc.

• Spool position feedback: 0–10 VDC

• Connector: M18, 6‑pin + PE, IP65

• Ambient temperature: −20 °C … +60 °C

• EMC: CE compliant

Pin Assignment (6+PE)

1. +24 VDC Power

2. Power GND

3. Command +

4. Command −

5. Spool position feedback (0–10 V)

6. Feedback GND

   PE: Protective Earth

Use shielded twisted pair for signals.

5. Key Features

• Pilotless direct drive: Permanent magnet linear force motor, no pilot oil needed

• High flow density: Highest flow version in D634 series

• Pressure‑independent dynamics: Stable response regardless of load pressure

• Integrated closed‑loop control: LVDT spool position feedback

• Fail‑safe: Spring‑centered, returns to neutral on power lossMoog Inc.

• Heavy‑duty construction: PWM electronics, IP65, EMI hardened

6. Typical Applications

• High‑force hydraulic presses, forging & extrusion lines

• Large structural test benches (aerospace, automotive)

• High‑load vibration simulators

• Industrial closed‑loop control (position/velocity/pressure)